/Engine/Source/Runtime/SlateCore/Public/Input/Reply.h
An event should rarely invokeFReply::CancelFocusRequest. This will change the reply so that it no longer contains a request for the system to set or clear focus. This is most useful when a reply has been cached for use in async operations.
[FReply](API\Runtime\SlateCore\Input\FReply) & CancelFocusRequest()